I thought that after posting nearly half a million words, people would understand that Mc is a sociopath.
I will translate it:
When he became the top 3 strongest beings, he didn't see it that way. For him, it was that everyone else became weaker.
After all, the purpose of strengthening experiments was that he could wield his tech better. He even said that when he tested his suits, there was no value in that strength in his eyes apart from that.
With underworld conquest, it was even easier to understand it was a move to expand his garage space and get more data.
The only value he has and takes his pride in is his creations, apart from that he has no reason not to listen to his mother as nothing changed to make it different.
The changes: Everyone got weaker, 'we have more labour work' Marcus pointed it out to his mother, and his garage got bigger. Thats about it.
There you have it for all the mother-haters stuff through eyes of sociopath who wants to build stuff and live his slice of life (there is a tag for that, too!)